Been bored today? Chances are you logged into Mail Online. Seven clicks later, you remembered who you were. Mail Online is the biggest newspaper website in the world. Comscore says 6.5m unique browsers turn up daily, and as the parent company's trading statement showed today the money is beginning to roll in.

Viscount Rothermere's DMGT reports results to year ending in September. Last year Mail Online generated a modest £16m. So far this year, growth is 69% - which would imply an outturn of £27m this year. The year after DMGT is aiming for £45m, which would amount to growth of another 40%, numbers it hopes to deliver by putting more hands on the keyboards in the US and elsewhere outside its Kensington fortress.

Elsewhere, or rather over here, the Guardian, the world's number three newspaper site with daily visitors of 3.1m at the moment is also showing revenue progress. Digital advertising revenues were £14.7m, ahead 26% in the year to March 31. That's not as fast as the Mail, perhaps, but solid enough progress - and the word from upstairs is that rate of growth has continued into the current financial year, that is through April and May.

Compare this, then, to those living behind a paywall. Subscriber growth has been impressive enough over the past year - digital subs for the Times were 131,162 in June 2012, ahead 26% compared to July 2011. But latterly subscriber growth has slowed right down. There were 129,000 subscribers in February, meaning that only 2,100 have signed up since. Not surprisingly the News International title has already resorted to a price rise to lift revenues - doubling its tariff to £4 a week for its iPad product. Web only readers still only pay £2 a week.

Assume everybody pays out £4 a week for the iPad, which is a little generous, would imply annual revenues of about £27m gross - less Apple's inevitable cut. Which takes revenues down to £19m. There will of course be some advertising revenues on top, but these are unlikely to be on the scale of Mail Online or the Guardian, or even close to it, as web advertising is a volume game and a paywall British product is unlikely to win many overseas subscribers.

What is emerging, then, is significant. Without jacking up prices further (which carries its own risk when it comes to keeping subscribers), the paywall project at the Times titles appears to have hit a limit. Meanwhile, there is still healthy double digit growth in digital advertising for at least a couple of newspapers. Once digital advertising revenues exceed £30m - which should happen in 2013 for at least one title - that could amount to a level that a paywall only publisher cannot easily match.